Fun to Imagine

Richard P. Feynman

BBC 1983 – transcript by A. Wojdyla

This is a transcript of the R.P. Feynman’s “Fun to imagine” aired on BBC in 1983. The transcript was made by a non-native english speaker (perdon my French!), so there might be some blanks (**) that were reproduced here. On overall, it should be fine though. I’ve also try to keep close to the very idiomatic language of the speaker. Grammar mistakes are actually his…!
A translation to French is available here

It's Interesting that some people find science so easy and others find it kind of dull and difficult
especially kids; you know, some of them are just heated up, and I don't know why it is. It's the same for all... (**)
For instance some people love music and I could never carry a tune. I lose a great deal a pleasure out of that
and I think that people lose a lot of pleasure who find the science dull.
In the case of science, I think that one of the things that make it difficult is that it takes a lot of imagination.
It's very hard to imagine all the crazy things that things really are like.

Jiggling atoms

Nothing is really as it seems used to be (**)
The hot is the speed at the atoms are jiggling; if they jiggle more, it corresponds to the hotter, and colder is jiggling less.
So if you have a bunch of atom, like a cup of coffee or something, sitting on a table, and the atoms are jiggling a great deal
and they bounce against the cup, and the cup gets shaking, and the atoms in the cup shakes, and the bounce against each other, so the heat heats the cup.
Hot things spread that heat to other by mere contact, because the atoms are jiggling a lot in a hot thing shake the ones that are jiggling only a little bit in the cold thing
so the hot (heat we say) goes into the cold thing, it spreads;
but what is spreading is just jiggling, an irregular motion, but it is easy to understand.

It brings up another thing that's kind of curious: that the -- when I say that things jiggle (**) like the ball bounces, you know they slow up and stop after a while.
But we have to imagine with the atom prefect elasticity, they never lose any energy; anytime they bounce they keep on bouncing, they don't lose anything, and they’re perpetually moving.
And that the things that happen when we say something loses energy, like the ball coming down and bouncing, it shakes irregularly some of the atoms in the floor, and when it comes up again, it leaves some of the atoms moving, jiggling.
So as it bounces, it is passing its extra energy, its extra motion, to little patches on the floor each time it rebounces and it loses a little heat each time, until it settles down, we say as the falling motion stops.
But what's left is the floor is shaking more than it was before, and the atoms in the ball are shaking more than they were before, that the organized motion of all these atoms moving the same way falling down, and the quiet floor, is now transformed into a ball sitting on the ground.
All the motion is still there in the form of energy of motion, in the form of the jiggling of the floor which is a little bit warmer (unbelievable!).
But anybody who has hammered a great deal of something knows that it's true, that if you (pound**) something a lot, you can feel the temperature difference: it heats up. It heats up simply because you are jiggling it.

This picture -atoms- is a beautiful one if you keep looking all kind of things this way.
In a little drop of water -a tiny drop-, the atoms attracts each other; they like to be next to each other, they want to have as many partners as they can get.
Now the guy at the surface has only partners on one side, it has air on the other side; he tries to get in.
And you can imagine this of people, this team in people, all of them moving very fast, all try to get -have- as many partners as possible; the guys on the edge are very unhappy and nervous and they keep pounding in, trying to get in, and that makes a tight ball instead of a flat.
That's surface tension, you realize when you see sometimes that a water drop sits like this on a table, and then you start to imagine why it's like that -because everybody is trying to get in to the water. And -- At the same time while all this is happening, other atoms leaving the surface, and the water drop is slowly disappearing.

I find myself trying to imagine all the kind of things all the time, and I get a kick out of it like a runner gets a kick out of sweating. I GET A KICK of thinking about these things!
I can't stop. I can talk forever!
If you could cool off the water so that the jiggling is less and less, it jiggles slower and slower, then the atoms get stuck in a place, they like to be with their friend; there's force of attraction and they get packed together, they're not rolling over each other, they're in a nice pattern, like oranges in a cradle(**), in a nice, organized patch(**).
All of them are jiggling in place, but not having enough motion to get loose of their own place and to break the structure down. And that what I'm describing is a solid -ice-, it has a structure. If you held the atom in one end in a certain position, all the rest are lining up in a position sticking out, and it’s solid at the end. Whereas if you heat that harder, then they begin to get loose and roll all over each other, and that's the liquid. And if you heat that still harder, then they bounce still harder, and they simply bounce apart from each other and they're just individuals, isolated atoms - I said atoms, these are really little groups of atoms: molecule- which come flying and hit and all over they have (**) the tendency to (**), they're moving too fast, their hands don't grab so to speak, and they fly up again, and this is the gas called steam.

You can get all kinds of understanding. When I was a kid with this "air", I was always interesting. I've noticed that when I pumped up my tires on the bicycle (you can learn a lot by having a bicycle).
It pumps up the tire and the pump will get hot, and I also understand that as the pump handle comes down and the atoms are coming up against it and bounce, and it's moving in (**), the ones that are coming off have a bigger speed than the ones that are coming in, so that as it comes down, each time they collide, it speeds them up, and so they're hotter when you compress the gas it heats.
And when you pull the piston back out, then the atoms that are coming faster than the piston feel a sort of seeding, give (**) and come out with les energy. It's like going against something that is so after (**) boomp boomp and it loses. So as you pull the piston out, and the atoms are hit, they lose their speed and they cool off. Then he gas gets cool as it expands. And the fun of it is that all these things, which you certainly noticed in the world about it : the pump, heats the gas, whether the gas cools when it expands(**), whether the steam evaporates until you cover the cover, and all these things you can understand from this simple picture.
And that's a kind of lot of fun to think. I don't want to take this stuff seriously;I think we should just have fun imagining it, not worry about. There is no teaching when you are asking a question at the end, otherwise it's a horrible subject.

Rubber bands

Most elastic things like steel springs and so on are nothing but these electrical things pulling back and pulling atoms a little bit apart when you bend something, and then they try to come back together again. But rubber bands work on a different principle: there are some long molecules like chains. And other little ones that are shaking all the time (*bump on the other little chains). And the chains are all kind of kinky (*). When you pull up the rubber band, the string gets straighter.
But these strings are being bombarded on the side by these other atoms trying to shorten them, by kicking them.
So it pulls back (it's trying to pull back), and this pulling back is only because of the heat.
So if you hit a rubber band, it will pull more strongly. For instance, if you hang a weight on the rubber band with a little mass, it is kind of fun to watch it rise (*), and there's another thing you could check this idea is right (that it's heat that drives the rubber band): if you pull the band out, just like you push the piston on the gas, if you pull the band out, these tightening string hitting the moleculesmakes them move faster, and so it is warmer. And if you take the band and let it in, then the molecules hitting the strings which sort of give as the thing heats, they give in to the the(*), and they lose energy when they hit this retiring band, straight string.

So it cools. And there is a little way you could do this (you're not very sensitive; it's a small effect). If you take a fairly wide rubber band, and put it between your lips, and pull it out, you'll certainly notice it's hotter. And then if you then hold it out and let in, you will notice that it is cooler; at least you will notice there's a certain difference in what happens when you expand it and when you contract it. And (*Ivory's) found rubber band fascinating to think. When they're sitting on an old package of paper for a lonnnnnng time, holding those papers together, it is done by a perpetual pounding pounding pounding, and these atoms that gets these chains to hold it, trying to keep them and keep them, year after year (well, rubber bands don't last that long, but, heyy... a long time), trying to hold this whole thing together.
The world is a dynamic mess of giggling things if you look at it right. And if you magnify, you will hardly see a little thing anymore, because everything is jiggling in its own pattern, and there's a lot of little balls. It's lucky that we have such a large scale of view of everything, that we can see these as things, without having worry about all these little atoms all the time.


The atoms like each other to different degrees.
Oxygen, for instance in the air, would like to be next to carbon, and if they get near they snap each other. If they're not too close though, they repel and they go apart, so they don't that they could snap together.
It's just as if you have a bowl (**) and are trying to climb a hall where there' a hole you can go into -the volcano hole- a deep one, it's rolling along and doesn't go down in the deep hole because it starts to climb the hill and goes away again. But if you make it go fast enough, it'll fall into the hole.
And so, if you take something like wood and oxygen; there's carbon in the wood from the tree, and the oxygen comes and hits the carbon, but not hard enough; it just goes away again -the air is like… nothing.
If you can get it faster, by heating it up sometimes, somewhere, somehow, get it started, a few a them comes fast, they go over the top surface, they come closer to the carbon and then snap in, and that keeps a lot of jiggling motion (**), which might hit some other again, making those go fast, so they can climb up and bump against other carbon atoms, and jiggle and they make other jiggle, and you get an horrible catastrophe, where all one after the other are going faster and faster and snapping in and the whole thing is changing. That catastrophe is a fire.

It's just a way of looking at it, and these are happening, it is perpetual, once the thing gets started, it keeps going, the heat makes other atoms capable of reaching, to make more heat, to make other atom... and so on!
So this terrible snapping is producing a lot a jiggling, and if I put all that activity of the atoms, I could put a cup of coffee over that (**). Messy wood! That's giving a lot of jiggling. That's what the heat of the fire is.
And then of course, you see what's happening when you start it, it goes on and on(**).

When it get started, why is that the wood has been surviving all this time with the oxygen all this time, and it didn't do it earlier or something? Where did I get this from? Why did it came (**) from the tree. And the substance of the tree is carbon, and where does it come from? That comes from the air, it's carbon dioxide from the air. People cut trees and think that it comes from the ground. The plant grows out from the ground. But if you asked "where the substance come from?", you find out where does it come from (**) the tree is coming out of the air? They surely come out of the ground! No, they come out of the air! The carbon dioxide in the air goes into the tree, and changes it, kicking out the oxygen, and pushing the oxygen away from the carbon, and leaving the carbon substance (topped) with water. Water comes out of the ground, you see; only is that it has to get there out of the (**) air, it came down from the sky. So in fact most of the tree is out of the ground -I'm sorry: it's out of the air! There's a little bit from the ground: some minerals and so forth.

Now, of course I told you that the we know oxygen and carbon sticks together tight (**)
How is that the tree is so smart to take the carbon dioxide (which is carbon and oxygen nicely combined), and undo that so easy?
Ah! Life! Life has some mysterious ways!
No! The sun is shining, and this sunlight comes down and knocks this oxygen away from the carbon, so it takes some light to get the plant to work! And so the sun, all the time, is doing the work of separating the oxygen away from the carbon, the oxygen is sort a of terrible by-product, which it spits back into the air, an leave in the carbon and water to make the substance of the tree. And then we take the substance of the tree to get the fireplace. All the oxygen made by these trees and all the carbons would much prefer to be together again. And once you let the heat to get it started, it continues and make an awful lot of activity while it's going back together again, and all those nice light and everything comes out, and everything is being undone, you're going from carbon and oxygen back to carbon dioxide, and the light and heat that's coming out is the light and heat of the sun that went in, so it's sort of stored sun that is coming out when you burn it.
Now the next question: how is the sun so jiggly, so hot? I gotta stop somewhere; I leave you something to imagine


- If you get hold of two magnet and you push them, you can feel this pushing between them. Turn it the other way and they stick together. Now, what is it, the feeling between those two magnets?
- R. Feynman (a bit angry): what do you mean "what's the feelingbetween two magnets when you hold them"?
- I mean that the sensation that they're something there when you push the two magnets together.
- R. Feynman: Answer to my question. What is the meaning when you say that "there's a feeling"? Of course, you feel it. Now, what do you wanna know?
- What I want to know is what's going on, between these two bits of matter.
- R. Feynman: They repel each other.
- Well then, what does that mean? Or why are they doing that? Or how are they doing that? I'm not saying... That's a perfectly reasonable question.
-Feynman (thinking): Of course it's a reasonnab... an excellent question.
Okay....... Huh......

But the problem is what you are asking me. You see, when you ask "Why something happens", how does a person answers "why something happens?"? For example...
Aunt Annie is at the hospital.
Because she slip, she slip on ice and broke her hip.
That satisfies people. It satisfies, but it would not satisfy someone who came from another planet and knew nothing about.
For instance, they should question: "Why when you break your hip you go to the hospital? How do you get to the hospital when the hip is broken, because... her husband seen that she had her hip broken, called the hospital up and send somebody to get her...
Well, that is understood by people. Then when you explain a "why?", you have to be in some framework that you allow something to be true.
Otherwise you are perpetually asking why. Why did the husband call up the hospital? Because the husband is interested in his wife's welfare. Not always the husbands are interested in their wives' welfare, when they are drunk and they are angry...
So it begins to be a very interesting understanding of the world, and all its complications.
If you try to follow anything up, you go deeper and deeper in various directions.
For example: why did she slip upon the ice. Well I know it's slippery. Everybody knows that, it's no problem. But you ask "why is ice slippery?". That's kind of curious. Ice is extremely slippery, it's very interesting. You say "How does it work?". You see, you could say either "I'm satisfied that you have answered me "Ice is slippery", that explains it"" or you could goon and say "Why is ice slippery? » And they're you're involved into something, because there are not many things as slippery as ice. It's very hard to get greasy stuff, but there's a sort of wet slimy (*). But a solid that is so slippery? Because it is in the case of ice, than when you stand on it (they say), momentarily the pressure melts the ice a little bit, so you get a sort of instantaneous water surface on which you are slipping. Why on ice and not on other things? Because water expands when it freezes, so the pressure tries to undo the expansion and melts it. It is capable of other things. But substances crack when they're freezing and you are pushing they are satisfied to be solid.
Why does water expands when it freezes, and other substances do not expand when they freeze? Alright?
I'm not answering the question, but I am telling you how difficult a "why" question is. You have to know what it is that you are permitted to understand, and allowed to be understood, and known, and what it is you are not. You have noticed in this example that the more I ask why (it gets interesting afterwards that the deeper the thing is the more interesting the thing is), and you can even go further and say "Why did she fall down when she slip?" That has to do with gravity, and involves all other planets, and everything else; never mind, it goes on and on!

And when you ask for example "Why two magnets repel?", there are many different levels, it depends on whether you are a student of physics or an ordinary person who doesn’t know anything or not. If you are somebody that doesn't know anything about, all I can say is that it is the magnetic force that makes things repel. And that you are feeling that force. You see, that is very strange because I don't feel kind of force like that in other circumstances. When you turn them in the other way they attract. There is a very analogous force: electrical force that is the same the same kind of that of the question and that is also very weird. But you are not at all disturbed by the fact that when you put your hand on the chair, it pushes you back. But we have find that looking at it that it is the same force as a matter of fact, the electrical force (not magnetic exactly in that case), but it is the same electric repulsions that are involved in keeping you finger away from the chair, (because everything is made out...) it is electrical force in minor, microscopic details (there are other forces involved, but they are connected to electrical force). It turns out that the magnetic and the electric forces for which I wish to explain these things (this repulsion), is what ultimately is the deeper thing and we have to stop, but we can start with to explain many other things that look like they were...
Everybody would just accept them. You know you cannot put your hand through the chair; that's taken for granted. But that you cannot put your hand through the chair when you look at it more closely: "WHY?". But it involves the same repulsive forces that appear in magnets. The situation is then to have to explain "why in the magnet it goes over a bigger distance than ordinarily?". There it has to do with the fact that in iron, all the electrons are spinning in the same direction, they all get lined up and they magnify the effect of the force, until it is large enough and that at a distance you can feel it. But it is a force that is present all the time and very common: it is a basic force (or almost; I could go a little further back if I went more technical), but in the early level, I just have to tell you that is going to be one of the thing you will have to take as an element in the world, the existence of magnetic repulsion (or magnetic attraction).
I can't explain that attraction in terms of anything else that is familiar to you. For example, if we say that the magnets attracts as if they were connected by rubber band, but I would be cheating you, because they do not behave as rubber bands; I should be in trouble: you'll soon ask me about the nature of the band. And secondly, if you are curious enough you will ask me "why rubber bands tend to pull back together". I would end up explaining that in terms of electrical forces, which are the very things I try to use the rubber band to explain: I would have cheated very badly, you see. So I am not going to be able to give you an answer to "why magnets attract each other", except to tell you that they do, and to tell you that's one of the elements in the world among different forces: there are electrical forces, magnetic forces, gravitational forces and others, and also some of the parts(*).
If you are a student, I can go further and tell you that the magnetic forces are related to the electrical forces very intimately, that the relationship between the gravity forces and the electrical forces remains unknown, and so on. But I really can't do a good job, any job that explains magnetic forces in terms of something else that you are more familiar with, because I don't understand it in terms of anything else that you are more familiar with.

The mirror

I went to a scientific school, MIT, and then fraternity, when you first join, they try to keep you from thinking if you think you're smart, from being too smart if you're feeling that you're too smart,
by giving you a lot of what look like simple question to try to figure out... what actually happens... is like training for imagination. It's kind of fun and I thought I'd tell you some that I remember. I learned them, of course and when you learn them, next time someone comes along with this wonderful puzzle: you look at them quite of quietly and you wait two or three or five seconds to show that you are thinking, and then you come up with this answer who astonish your friend, but the fact was of course that you were trained by your fraternity brothers (**) earlier on.
One of the questions that used to that regard was a problem about the mirror; it' an old fashioned, it's an old problem.
You look in a mirror, and let's say you part your hair in the right side, and you look in the mirror and the image of the skull part on the left side, so the image left to right mixed up! It's not top and bottom mixed up, because the top of the image of the head is on the top and the bottom of the feature is at the bottom, and the question is how does the mirror know to get the left and right mixed up and not the up and down? You get a better idea of the problem if you think of lying down and looking at the mirror: Your hair is still on the left side, and now the left and right is the up and down! Whereas the up and down which look okay where the left and right before: the mirror somehow sort of figured out what you are gonna do when are looking at it, so what to describe in a sort of symmetrical way what the mirror does, that it doesn't look lopsided and it takes left and mixes it up with right and doesn't do the same with up and down. And after a lot of fiddling (**) the answer to that one.
You see, if you waive this hand, then the hand in the mirror that waves is the right opposite at it. The hand on the east is the hand on the east and the hand on the west is the hand on the west, and the hand that head that up is up and the feet that is down is down. Everything is really all right! But what's wrong is if this is north (/pointing at the camera), the nose is to the north of the back of your head, but in the image the nose is to the south of the back of the head, so what happens really in the image is neither the left and the right mixed nor the top and the bottom, but the front and back had been reversed, you see , that is just the nose of the thing is on the wrong side of the head of you want it, alright? Now ordinarily when we think of the image we think at it as ofanother person, and we think the normal way that another person would get on that condition over there. It's a psychological thing. We don't think of the idea that the person has been squashed and pushed back forward (**) with his nose and his head, because that's not what ordinarily happens to people. A person gets to look like you looks in the mirror by walking around and facing you. And because people when the walk around don't turn their head for their feet (we leave that part alone), but they get their right and left hand swung about you see when they turn around, so we say that's it's left and right (into**) change, but really the symmetrical way is along the axis of the mirror that thing get into change. That's an easy one. A harder one, and very entertaining, was "what keeps a train on the track?"

The train

"what keeps a train on the track?"
And of course the answer is, as everyone thinks: the flanges on the wheel (you know the wheel have some kind of flange on it). But that's not the answer. Because flanges are just safety devices. If the flange rubs against the track, you hear a horrible squealing, then just in case the real mechanism doesn't work. There's another mechanism with train that is connected to it. People all know this about their automobile, than when you go around the corner, the outside wheel has to go further than the inside wheel. And if the front-- if the wheel were connected on a solid shaft, you couldn't do that, you can't turn the outside wheels further that the inside wheels, and so the shaft is broken in the middle with a gear system called a differential. Did you ever see a differential on a railroad train? No!

You look at those wheel on the (**), and then there are to wheel and there is a solid steel rod, going from one wheel to the other; there's nothing-- one turns the same as the other. So now how does it go around a corner? A curve, when the outside wheel has to go further that the inside wheel? And the answer is that the wheels are flanged like this (/show a tapered flange) --I mean not flange, they're cones (this way), that is there's a little fatter, closer to the train, and a little thinner further out. If you look closer, you see they've got this (**) edge. And it's all very simple: when they go around the curve, they slide out on the track bed, so that this wheel (/show a turning wheel) travels on a fatter part (bigger diameter) and on the other on the small diameter, so when the both turn one turn, this swings further than the other. And that's what keeps it on the track also the same way. Suppose the train is running along on this thing, on the track; if the track is here and the two wheels are exactly balanced (and it's nice and even), suppose accidentally it gets a bump or something and slides out this way, the this wheel (/show a wheel) is on a bigger circumference than this one, but they're on a solid shaft, so when it turns once around, it carries this wheel forward relative to they others and steers the train back on the track (of course, when it gets to far it goes on the other side), and it stays on the track because the wheel are tapered, and the flange is safety. But we had a lot of stuff like that, and we had to learn and get straight before we became full-fledged member of the fraternity.

Seeing things

If you are sitting next to a swimming pool, somebody dives in, and she's not too pretty, so I can think of something else, I can think of the waves that forms in the water, and when lots of people have dived in the pool, there is a very great choppiness of all these waves all over the water, and to think that it is possible maybe that waves there is a clue of what is happening in the pool.
That some sort of insect or something with efficient cleverness could sit in the corner of the pool and just be disturbed by the waves. And by the nature of the irregularities and bumping all the way, it figures out who jumped in and where and when and where what is happening all over the pool.
And that's what we do when we are looking at something. The light that comes out is wave, it's just like in the swimming pool, except in three dimensions instead of just two dimensions of the pool, going in all the directions, and we have an one eighth inch (*) black hole two which these things go, which is particularly sensitive to the parts of the waves that are coming in a particular direction (they're not particularly sensitive when they come from the wrong end, what you say is the "corner of our eye".
And if you want to get more information about the corner of your eye, we swivel these balls about the sort of hole they're in. Then it's quite wonderful that we see can figure out so easy (it's easy because the lightwaves are easy; the waves in the water are a little bit more complicated: it would have been harder for the bug than for for us, but it is the same idea: to figure out what the thing is that we are looking at a distance.
And it is kind of incredible, because when I am looking at you, someone standing to my left could see somebody who is standing on my right, and that the light can go right across these waves, the waves that are going this way (show up and down), id. (Front/back). It is just a complete network. Now you think of arrows passing each other, but that's not the way it is, because all of this is something shaking (it is called the electric field), but we don't have to bother with what it is. It is just like the water height that is going up and down. Some quantities are shaking about here, and the combination of the motion that is so elaborate and complicated then that results in what make me see you. And at the same time, completely undisturbed by the fact that another influence represents the other guy seeing the other on this side. So that this is a TREMENDOUS MESS of waves, all over in space, which we call the light bouncing (*) around the room, and going from one to the other, because of course most of the room doesn't have one-eighth inch black hole : it is not interested in that light, but the light is there anyway: it bounces of it, it bounces of that, and all of this is going on , and yet we can sort it out when this instruments (Feynman shows his eye).
But besides all this, these little waves I was talking about in the water, and those so big that you can (*) have slowest swashes which are longer and shorter, perhaps the animal who is making his study only uses waves between this length (F. shows a short distance) and that length (other length), so it turns out that the eye is only using waves between this length and that length, except that those two lengths are hundred thousandth of an inch. And what about the slowest swashed, the waves that go more slowly that happen to have the longer distance between crest to (top**) .
Those represent heat. We feel those, but our eyes don’t see them focused very well; we don't see them in fact at all. The shorter wave is blue, the longer wave (as you know) is red, but when it gets longer that we call infrared. All of these come a ** the same time; that's the heat. Pit viper that get down here in the desert, they have a very little thing (F. shows a hole) so that they can see longer waves, and pick up mice, which are radiating their heat in the longer waves (but their body heat) by looking at them with this eye, which is the pit of the pit viper.
But we can't, we are not able to do that. And the these waves get longer and longer, and (all through the same space, all of this things are going on at the same time), so that in this space there is not only my vision of you, but also information from my skull radio that is being broadcasted at the present moment, and the seeing of somebody from Peru! All the radio waves are just the same kind of waves, only they are longer waves. And there's the radar, from the airplane which is looking at the ground to figure out where it is, which is coming to the room at the same time. Plus X-rays, cosmic rays and all of these other things that are the same kind of waves, EXACTLY the same kind of waves, but shorter, faster or longer, slower. It is exactly the same thing.
So this big feel, this area of irregular motion of this electric field, these vibrations, contains this tremendous information. And it's all really there!
That's what gets you! If you don't believe it, then you take a piece of wire, and connect it to a box. And in the wire, the electrons will be pushed back and forth by this electric field, swashing just at the right speed for that certain kind of long waves. And you turn some knobs on the box to get the swashing just right, and you hear Radio Moscow! And you know that it was there. How else would have it get there? It was there all time. It's only when you turn on the radio that you notice it. But that all these things are going through in the room at the same time. Everybody knows, but you've got to stop and think about it, to really get the pleasure about the complexity, the inconceivable nature of Nature.

Big numbers and stuff

When we were talking about the atoms, one of the trouble we have with the atoms is that they are so tiny and it is so hard to imagine the scale.
The atoms are in size compared to an apple is the same scale as an apple is compared to the size of the earth. That's kind of a hard think to take, and you have to go through all these things in one time, and people find these numbers unconceivable, and I do too. And the only thing you do is just change your scale, you just think of small balls but you don't try to know exactly how small they are too often. It gets kind of a bit nutty, alright? But in astronomy, you have the scales that get reversed! Because the distance to the stars is so enormous. You know that light goes so fast, and it only takes few seconds to go to the moon and back, or it goes around the earth in a seventh and a half of a second, it goes for years... two years, three years before it gets to the nearest that there is to us! But all our stars are in nearby galaxies, a big mess of stars which is called a galaxy. But our galaxy is hundred thousand light-years. And then there's another patch of stars. It takes a million years for the light to get here, going at this enormous rate. And you just go crazy trying to get too real that distance. You have to do everything in proportion. That's easy, say that a galaxy is a little patch of stars and there's another then times apart what they are big. That's an easy picture. But you just go to a different scale. Once in a while you just go back to earth scale to discuss galaxies'. But it' kinda hard.
The number of stars we see at night is only about five thousand. But the number of stars in our galaxy, the telescope have shown when you improve the instruments - oh, you look at the stars, you look at the galaxy, all the light that we see, the little tiny influence, spread from the stars over this enormous distance (three light-years for the nearest stars) on! on! on! the light from these stars is spreading, the wave front is getting wider and wider, weaker and weaker out in all of space to finally the tiny fraction that comes in one square eighth of an inch little black hole and does something to me so I know it's there! You know a little bit about it, I'd rather gather a little more of this tiny fraction of the front of light; and so I make a big telescope which is a kind of funnel. The light that comes over this big area (two hundred of inch in cross) is very carefully organized, so it is all concentrated back so it goes to our pupil. Actually it's better to photograph, and nowadays they use photocells which are better instruments, but anyway the idea of a telescope is to focus the light from a bigger area into a smaller area so that we see things that are weaker, less slight, and that's how we find there's a very large number of stars in our galaxy. There's so many that if you try to name them, in one second, all of the stars in the galaxy (there are billions of stars in the universe, just the stars in the galaxy here), it takes three thousand years! And yet that's not a very big number! Because if those stars were to drop one dollar bill on the earth (during a year each star dropping one dollar bill), they might take care of the deficit, which is suggested for the budget of the United States!
So you see what kind of numbers we have to deal with! And anyway I think that the numbers are a problem, in astronomy the size is a number, and the best thing to do is to relax and enjoy those! The tininess of us and the enormity of the rest of the universe. Of course, if you're feeling depressed by that, you know how to look in the other way and how big you are compared to these atoms and the part of the atoms and then you're an enormous universe to these atoms and you just stand in the middle and you enjoy everything both ways!
But the great part of astronomy is the imagination that is necessary to guess what kind of structures, what kind of things can be happening to produce the light and the effect of the light of the stars that we do see.
And I could take an example: many times in science, by using imagination you imagine things which could be according to all the known knowledge and the laws. And you don't know whether it is yet or not. And that's very interesting, there is a creative imagination (imagination you call it, it's not just imagining thing that are relatively easy, but something different). And to take an example of, a star as we understand it to ordinary stars like the un, which is just a big ball of gas, of hydrogen (that's the burning of hydrogen and so forth), and it's an enormous mass of gas, and it's held together by gravity (you don't to always understand gravity as a curved space; it's good enough for the purpose a force inverse to the square of the distance). When the things are closer together, the force is stronger. And it pulls everything together. By the way that's why the world is round: because global matter is closed together as much as possible, if we had a great mountain or a great irregularity like a bump, it would be pulled in by gravity and gets smoother
Rocks and stones are bump that aren't much bigger than a few miles, (**) and mountains are the biggest bumps. But on the moon where the gravity is less, the bumps are higher; the mountains are bigger on the moon.
Anyway, to get back to the star, it's all held together by gravity and it has got a nuclear fuel that is burning up the hydrogen and making the energy which keeps them going. And after a while, it reduces the fuel a lot (and people thinks about what will happen then). And it would be possible that just be gas, sort of hanging around, held together by gravity, but quiet. But another possibility is to think: if I push the stuff together closer, the gravity is stronger, will it hold it together. If we push a little bit together, the pressure increases (when you push the gas together, there are more atoms and they pound on it so the pressure is higher, but the gravity stronger: it turns out the pressure wins so it would just come out again. If you push a star like take (Feynman oscillating hands) it oscillates, and there are some stars that are oscillating and vibrating and so on).
But it turns out that if you keep on analyzing and push it very far into an incredible concentration of those, the whole mass of the sun is down to the size of the earth or smaller, then it turns out that all the nuclear matter, all the nuclei of the atoms are stuck next to each other. They're tight, the space where the electrons is all squased out, and it comes out that when you get to THAT far, the gravity is strong enough to overpower the pressure again, even though the pressure has got to be enormous, the gravity has to be even more enormous, and the thing will stay steady at a different size and be nothing but a neutron, a nuclear matter, nothing solid in nuclear matter, and this a a possibility worked out by Oppenheimer and Volkov, and it's called a neutron star.
And people waited to see if there were any such neutron stars for years, to recently they found these pulsars which emit flashes of radio waves (later they found light) which goes thirty times a second (for the fastest ones), or maybe ten times a second, or one a second. And at first, that's very mysterious; you are used to stars being big and slow... how can anything in a star move in a thirtieth of a second? Well these things are very small neutron stars and they’re spinning very fast. For reason not yet understood, they are emitting a beam, a beam of radio waves like a search light in an airport, something that goes around boop boop boop, so we get the flashes tick tick tick, that fast. Imagine a star the mass of the sun, doing something, turning so fast (thirtieth of a second), another big number, hard conceive, imaginary things, and they call the idea that there could be a star of such an enormous density that a teaspoon would weight some much that if you put that matter on the earth it is so heavy that that it will just plough right to the center of the earth!
And for things like that, it took a lot of imagination: it comes out the mathematics and the analysis of all this helps you to make sure you are not making a mistake, and it turns out that such a star is possible, and it turned out a little bit later they do exist, and that's a good example of how imagination is a useful thing and it produces guessing all the time and you make answers by using it. Besides, the very difficult thing in imagination is to use things that might be up there to explain the things we see. And in the case of astronomy, we have a large number of things we see that we have no yet quite clearly got the imagination to see what is producing it.
Quasars are very powerful sources of light and radio waves, at great distance, and we see them because they are so bright. The exact cause of their sources is gradually been recently understood, in terms of another nutty concept of imagination: the black hole, which is something that comes from following the logic of gravity of Einstein to its ultimate, working out the consequences in crazy circumstances. Suppose you have a great amount of matter, so great that the gravity force is so much that even light trying to get out falls back. Nothing can go faster that light, and nothing could escape. You couldn't see it! Well, how do you get there? If you have a large amount of matter, it could fall together and get into this condition and no longer could the light come out. So you would have this thing which continues to attract things to it, things would go in and nothing would come out. That is called the black hole.
And you say how is going a black hole, which is absorbing everything; make all this energy that we see. Is that an explanation of a quasar? Actually, it may well be. Because if the things that are falling in don't go pluck in but go around, falling in by swirling, then as they are falling irregularly, and in the fast motion they produce this whirlpool that generates a lot of energy and friction and so forth, and different kind of effects by magnetic and electrical effects that could make jets of matter that come out of the quasar and the radio galaxies in ways that are not really understood. We don't have a real picture why there are jets of radio waves, matter emitting radio waves. In galaxies (there are galaxies with great jets coming out with big clouds of matter on each side which are emitting radio waves. So there is some kind of sources in there). It sort of getting wired up and shoots these jets of matter out with tremendous energy. And it's guessed that maybe it's a black hole somehow or other, and somehow or other is the challenge of the imagination. Which has not yet been answered. by anybody, with any great confidence.

Bigger is electricity!

The stuff of fantasizing in looking at the world, imagining things, which really isn't fantasizing because you just try to imagine the way it really is, comes up handy sometimes.
The other day I was at the dentist, he was getting ready with this electric drill to make holes, and I thought I'd better think of something fast or else it's gonna hurt.
And then I thought about this little motor going around, and what was that make it turn? And what was going on? and what's going on is that there is a dam at some distance and the wheel over the dam turns (a great big wheel, alright?), and this wheel is connected with long pieces of copper, which split up in other pieces of copper and split up and spread all over the city, and then they're connected back to another little gadget and makes wheels turn, all the wheels in the city are turning, because this little thing turns.
If this thing stops, all the wheels stop. If it starts again, they all start again. And I think it's kind of a marvelous thing of nature. It's extremely curious that phenomenon. I like to think about a lot, because all it is, it's copper and iron.
You see, sometimes we think it's man-made generator very complicated, the phenomenon is a result of something very special that we've made.
But it's nature doing it, and it's just iron and copper; if you just take a big long loop of copper, and add iron at each end and move the piece of iron here, the other iron move at the other piece. And if you get it down to the -nothing- you are just moving piece of iron in a loop a copper and see other piece of iron move, you realize what a fantastic mystery nature is!
And you don't even need the iron. (pump prime get started**) by giggling coppers strands fast around knocking them and knocking and so forth, you can get all the copper strands move at the other end, over a long connection.
And what is it? It's only copper! And motion! We're so used to circumstances in which these electrical phenomena are all canceled out. Everything is sort of neutral: pushing and pulling, it's all very dull. But nature has these wonderful things. Magnetic forces and electrical forces when you comb your hair. When you comb, you get this strange condition: if you put it in front of a piece a paper, that lifts up the paper, the paper giggles... at a distance, far away. And that's in fact, the fact turns out, that the thing that's deeper inside of everything that the things we're used to. We're used to forces that only act directly: light, you push with your finger, it only acts directly, but then you have to imagine what it is that's pushed by the finger. This finger is made of little balls of atoms. And it has got another bunch of atoms that are pushing it.
At that little space between those atoms. And that pushing is going through that space. And the only thing that happens with the comb and the paper is that the circumstances have a reason which makes it possible to see those forces go through a bigger distance than just the space between the atoms. What it is they have charges like electrons, that are both the same, they repel each other with a force. They are very tiny parts, they are piece of the atoms, and they repel each other with a force which is enormous (it's inverse to the square of the distance just like gravity is inverse to the square of the distance, but gravity is attractive whereas this one is repulsive) and these two electrons (the gravity is weak to the electricity: the electricity is so much more enormous that I can't express because I don’t know the name of the numbers : it's one with thirty eight or forty zeros after the one. Bigger is electricity! It's so enormous, that if I were all electrons... well, the number is to big!) .
There's also however for electrical thing other kind of charges, positive charges, for example protons are positive, they're inside the nucleus of the atoms and the attract electrons. Opposite charges attracts, alike charges repel. So you have to imagine enormous forces, where likes are trying to get away from likes, and unlikes are trying to get near the opposite. What would happen if you had a lot of them? All the likes would collect with unlike, they attract each other, and you get intimate mixture of pluses and minuses all on top of each other, very close together. You wouldn't have a lot of pluses anywhere, because they repel each other. They're all being compensated with minus very close, and then you get these little nuts of plus and minus.
They reason why the nuts don't get smaller and smaller is because they are particles and there are quantum mechanical effects that we won’t discuss that don’t make the decay any smaller than a certain size. So you get these little lumps with are balls, they are the atoms.
The atoms are positive and negative charges and they neutralize, they cancel their charges as nearly as they can. And because of these intimate forces are so big, it ends up nowhere. With very little left, because they're so big they cancels out, they're always exactly the same number of pluses and minuses in any normal material.
When you comb your hair, you rub just a little bit extra off, just a few extra minuses here, and somewhere else a few extra pluses. But the forces are so big that just the extra ones, which make a force that we can see, that seems to get over a long range, and that we find mysterious. And that we need an explanation for. And we try to find an explanation in terms of ideas like forces that are inside of rubber bands, or steel bars and twisted things. We would like to have some kind of puller, at a distance, because we're used to it. That we don't get any push until we're touching, but the fact is the reason that we don't get any push into a touchy (**) is that the same forces as you see at a long distance only comes down because the forces of the pluses and minuses are canceled out so that that you don't feel anything until it gets very very close. When it gets close enough of course it makes this difference between which is plus and which is minus and where they are and repel each other.
so it's kind of fun to imagine that this intimate mixture of highly attractive opposites which are so strong that they cancel out the effects and it's only sometimes, when you have an excess of one kind or another that you get this MYSTERIOUS electrical force. And how can I explain these electrical forces in any other way? Why should I try to explain it in terms something like jelly or other things which are made? And I understand the other way around in terms of strong, long distance forces which are all canceled out.
So it's the electrical forces in fact, and the magnetic forces in fact that we have to accept as the base reality, in which we are going to explain all the other things. So again it turns out it's hard to understand. you have to do a lot of imagining, that the real world has as its base a force that acts at long distance, that we haven't got much experience without force (except peculiar phenomena **)... that ordinarily, we don't have much experience without force is simply because that's what requires explanation. That's what requires imagination. The long distance force we haven't a picture for.
And in the example of the generator, what happens is that the electrons which are part of an atom, they're pushed by the motion of the copper wires, and one of the wonderful things is that if you push an electron little bit here, they get too close so that it pushes the other and they repel at a long distance, so it's not just like water which repel at a short distance but it's a wonderful fluid which repel at a long distance and in facts it goes very quickly through the wire, there is a little concentration which goes ZINNNG through the wire all over the city at once. And you can use that stuff to make signals, you can push a few electrons here by talking into a telephone, then at the other hand of the line, a long line of copper across the city, the electron responds because of this very rapid interaction over these long distances to what you say in this room. And they discovered, experimentally the existence of these long forces and that this rapid motion action was a tremendous thing for human beings.
I think that the discovery of electricity and magnetism and the electromagnetic effects which are finally worked out (the full equations were worked out by Maxwell in 1873) are probably the most fundamental transformation of.. the most remarkable thing in history, the biggest change in history.

11 - Ways of thinking

You ask me if an ordinary person, by studying hard, would get to be able to imagine these things, like I imagine. Of course! I was an ordinary person who had studied hard. There are no miracle people. It just happen they got interested in these things and they learned all these stuffs. There are just people. There's no talent, special, miracle ability to understand quantum mechanics or a miracle ability to imagine electromagnetic fields that comes without practicing and reading and learning and study, so if you say it take an ordinary person who's willing to devote a great deal of time and study and work and thinking in mathematics, then he has become a scientist.
When I'm actually doing my own things and working in a high, deep and esoteric stuff that I worry about, I don't think I can describe very well what it's like. First of all, it' like egg and chicken, which comes after which? It happens quickly and I'm not exactly sure what flashes and stuff are coming to head. But I know it's a crazy mixture of partial equations, partial solving in equations, then having some sort of picture of what is happening that the equation is saying it's happening, but they're not that well separated (the words I'm using) and it's a kind of a nutty thing, it's very hard to describe, and I don't know if it does any good to describe.
And there's something that struck me, it's very curious: I suspect that what goes on in every man's head might be very very different. The actual images or semi-images (**) that comes, and when we are talking to each other at these high and complicated levels, and we think we are speaking very well, that we are communicating, but what we are really doing is having a some kind of big translation scheme going on, translating what this fellow says into our images, which are very different. I found that out because in the very lowest level (I wouldn't go into much details but I got interested in...). Well I was doing some experiments and I was trying to figure out something about our time sense, and so what I would do is trying to count to a minute (actually I count to 48 and it would be one minute, so I calibrate myself and I would count a minute in 48 counts, it's close enough). As it turns out that if you repeat that gym, you do it very accurately: when you get to 48 or 47 or 49, not far off, you're very close to a minute.
And I was trying to find out what affected that time sense, and whether I could do anything at the same time I was counting. And I found that I could many things: I could (there's something that isn't nut). For example, I had great difficulty in the university, to get my laundry ready, and I was putting the socks out, and I had to make a list "how many socks" (there were something like 6 or 8 socks), and I couldn't count them, because the counting machine was being used, and I couldn't count them, until I found that I could put them in a pattern and recognize the number. And so I learned a way, after practicing, for which I could count the line of type in a newspaper (**) and see them in groups, three, three, three, one, that's a group of ten, without saying the numbers; that's grouping. I could therefore count the line of types I was practicing in the same time I was counting internally the seconds, so I could do this fantastic trick of saying "forty-eight, that's one minute and there are sixty seven lines of type you see!".
That was quite wonderful! And I discovered many things I could read while I was.., no, excuse me, yes, I could read perfectly all right I was counting and get an idea of what it was about. But I couldn't speak, I couldn’t say anything. Because of course I was sort of trying to speak to myself, inside, I would say "one, two, three" or sort of in the head. Then I went down to the breakfast, and there was John Tukey, who was a mathematician at Princeton in the same time, and we had many discussions, and I was telling him about these experiments and what I could do. And he said "that's absurd!". He said "I don't see why you have any difficulty talking whatsoever, And I can't possibly believe that you could read" . So I couldn't believe all this and we calibrated him (it was 62 for him to sixty seconds or whatever; I don't remember the numbers now), and then he said "alright, what do you want me to say? Mary had a little lamb. I can speak about anything, blah blah blah, blah blah, 62! that's one minute". He was right. And I couldn't possibly do that. And he wanted me to read, because he couldn’t possibly believe it. And we compared note, and it turned out that when he thought of counting, what he did inside his head was counted was he saw a tape with numbers with "clink, clink clink", the tape would change with numbers printed on it, he could see. So it was sort of an optical system that he was using, and not voice.
He could speak as much as he wanted, but if he had to read, then he couldn't look at his clock! Whereas for me it was in the other way. And that's where I discovered, at least in this very simple operation of counting, the great difference in what goes on in the head when people think they are doing the same thing. And so it struck me therefore, if that is already true at the most elementary level. That when we learn mathematics and Bessel functions, and the exponential and the electric field and all these things, that the imageries and the method by which we are storing it all and the way we think about it, could really, if we get to each other's head, entirely different. And in fact, while somebody sometimes has a great deal of difficulty to understanding a point which you see as obvious, and vice versa, it's maybe because it's a little hard to translate what you just said into his particular framework and so on. Now I'm talking like a psychologist, and you know I don't know nothing about this!
Suppose that little things behaved very differently that anything that was big. Anything that you are familiar with, because you that animal evolves and so on, and brain evolves and gets used to handling things as the brain is designed through ordinary circumstances.
But if the (**glock particles in the deep **) workings were by some other rules and some other character, they would behave differently (**), than anything on the large scale, then there would some kind of difficulty in understanding and imagining reality.

And that difficulty, we are in. The behavior of things in the small scale is so fantastic! It is so wonderfully different! so marvelously different that anything that behaves on a large scale. You said "electrons act like wave", no they don't exactly, "they act like particles", no, they don't exactly, "they act like a kind of a fog around the nucleus", no they don't exactly. And if you want to get a clear, sharp picture of an animal, so that you can tell exactly how it behaves correctly, and have a good image in other words, really good image of reality, I don't know how to do it. Because that image has to be mathematic: we have a mathematical expression, a strange mathematics, I don't understand how it is, but we can write mathematical expressions and calculate what the thing is going to do, without being actually able to picture it. It would something like a computer in which you put certain numbers in and you have a formula for what time the car will arrive at its destination,and the thing does the arithmetic to figure out what time the car arrives at the different destinations. But you cannot picture the car. It is just doing the arithmetic. So we know how to do the arithmetic, but we cannot picture the car. It's not a 100%, because for certain approximate situations, certain kind of approximate pictures work, that it's simply a fog around the nucleus that when you squeeze it repels you (it's very good for understanding the stiffness of certain material). That it's a wave that just does this and that is very picture for some other phenomenon. So when you're working with certain particular aspects of the behavior of atoms, for instance when I was talking about temperature and so forth, that it's just little balls, it's good enough and it gives a very nice picture of temperature, but if you ask more specific question and you get down to questions like "how is that when you cool helium down, even to absolute zero where it's not supposed to be any motion, it's a perfect fluid and it has no resistance and it flows perfectly, and it isn't freezing". Well if you want to get a picture of atoms as all of that in it, I can't do it. But I can explain why the helium behaves as it does, by taking my equations and seeing that the consequences of them is that the helium would behave as it is observed to behave. So we know that we have the theory right, but we haven't got the pictures that would go with the theory. And it's that because we haven't caught on the right picture, or it's because there aren't any right pictures for picture who have to make pictures out of things that are familiar to them.

Well let's suppose it's the last one, that there'sno right picture in terms of things that are familiar to them. Is it possible then to develop a familiarity with those things that are not familiar on hand, by studying, by learning the properties of atoms and quantum mechanics, by practicing with the equations, until it becomes a kind of second nature, just like it's a second nature to know that two balls came towards each other, they smash into bits. You don't say "the two balls when they come toward each other turn blue". You know what they do . So the question is whether you can get to know what things do without... better that we do today, as the generations develop, will they invent ways of teaching so that the new people will learn tricky ways in looking at things, and be so trained, so well trained, that they won't have our troubles, with the atom picturing.

There's still a school of thought that cannot believe that the atomic behaviors is so different than large scale behaviors. I think that's a big prejudice, it's a prejudice of being so used to large scale behaviors, and they're always seeking to find '(**) for the data we discovered underneath the quantum mechanics, there's some mundane, ordinary balls hitting or particles moving and so on, and I think they're gonna be defeated. I think Nature's imagination is so much greater than man's, she's never gonna let us relax!